Agronomy and Crop Sciences Commons^™

Arkansas Wheat Cultivar Performance Tests 2015-2016, R. E. Mason, R. G. Miller, D. E. Moon, J. P. Kelley

Arkansas Agricultural Experiment Station Research Series

Wheat cultivar performance tests are conducted each year in Arkansas by the Arkansas Agricultural Experiment Station, Department of Crop, Soil and Environmental Sciences. The tests provide information to companies developing cultivars and/or marketing seed within the state and aid the Arkansas Cooperative Extension Service in formulating cultivar recommendations for small-grain producers.

Diversity And Virulence Of Soybean Cyst Nematode (Heterodera Glycines Ichinohe) In Nebraska, Kyle C. Broderick

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Soybean cyst nematode (SCN, Heterodera glycines Ichinohe) is one of the most economically important soybean pathogens in the United States. Best management practices are the use of resistant cultivars and crop rotation. Though there are several genetic sources of SCN resistance, most of the SCN-resistant cultivars are derived from a single resistance source (PI 88788). Other states have reported an increase in virulence to PI 88788 due to prolonged use of this resistance. In this thesis, two studies were conducted to characterize the diversity and virulent phenotypes of SCN populations in Nebraska.

The first study assessed the virulent phenotypes of …

Effect Of Dung Beetles On Dung Decomposition And Nutrient Cycling In A Nebraska Rangeland, Kenneth Shay Evans

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Management practice can have impacts on the abundance and frequency of dung beetle populations and nutrient cycling in grazing systems. Also, agriculture and livestock production land use is a considerable source of anthropogenic greenhouse gas (GHG) emissions, which are known to be one of the causes of global climate change. In this study, we evaluated the effect of dung beetle presence on the fluxes of greenhouse gasses (GHG’s) from dung pats in the semi-arid Sandhills region of Nebraska, by using closed chambers to measure the fluxes of carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N …

Over-Summering Ecology Of The Wheat Curl Mite (Aceria Tosichella Keifer), Anthony J. Mcmechan

Department of Entomology: Dissertations, Theses, and Student Research

The wheat-mite-virus complex is a consistent and significant threat to winter wheat production in the western Great Plains. This complex consists of three viruses (Wheat streak mosaic virus, Triticum mosaic virus, and Wheat mosaic virus that are transmitted by the wheat curl mite (Aceria tosichella Keifer). Yield impacts from this complex are typically associated with the presence of volunteer wheat that emerges prior to harvest as a result of hail occurring during the heading stages of wheat in early summer. Historical literature on pre-harvest germination has been primarily focused on accelerating breeding programs; however, critical gaps in knowledge exist on …

The Biology And Management Of Waterhemp In Indiana, Joseph M. Heneghan

Open Access Theses

Waterhemp is a dioecious weed species indigenous to the Midwestern United states yet it has only recently become problematic in agronomic crop production in Indiana. Waterhemp is a small-seeded broadleaf which has increased in prevalence in conjunction with an increase in conservation tillage practices. Waterhemp germinates and emerges from the top 3 cm of soil and is known to exhibit extended periods of continual emergence, longer than most other summer annual weed species that are typically present in agronomic production settings. As a C4 species, waterhemp then grows rapidly and is capable of producing thousands of seeds, while effectively competing …

B. R. Wells Arkansas Rice Research Studies 2015, R. J. Norman, K.A. K. Moldenhauer

Arkansas Agricultural Experiment Station Research Series

No abstract provided.

Determination Of Optimum Fall And Spring Nitrogen Fertilizer Rate For Maximizing Grain Yield Of Soft Red Winter Wheat Sown At Variable Planting Dates, Lucas Vasconcelos Vieira

Graduate Theses and Dissertations

An optimum planting date is important for winter wheat nitrogen (N) management as it dramatically changes the growing environment including temperature and moisture, ultimately affecting fertilizer efficiency and grain yield (GY). In Arkansas, high precipitation in the fall often forces farmers to delay planting and current Arkansas recommendations include the application of fall N when soft red winter wheat (SRWW) is sown later than optimum, despite the lack of data supporting this practice. This study evaluated the effect of rate and timing of N application on GY of SRWW sown at variable planting dates in Arkansas. Granular urea was split …

Phenotypic And Gene Expression Analysis Of Diverse Rice Genotypes In Response To Drought, Miranti Rahmaningsih

Graduate Theses and Dissertations

Drought is one of the most limiting factors for rice (Oryza sativa L.) growth and development with vegetative and reproductive stages the most sensitive and distinct phases. During the vegetative stage, drought can cause reduction in growth and biomass accumulation. Moreover, water stress at reproductive stage can reduce yield significantly. Plants are protected against drought by three different mechanisms: drought avoidance, drought tolerance, and drought escape. An integrated approach combining physiology, breeding, and genomics could be an effective way to characterize and mitigate this problem. The objectives of this research were to (1) screen a diverse set of rice genotypes …

Characterization Of Echinochloa Spp. In Arkansas, Hussain Tahir

Graduate Theses and Dissertations

Echinochloa species are the most problematic grass weeds in rice and soybean production throughout the southern United States. The species under this genus has high intra- and interspecific variability, with many ecotypes, observed within a species. This study was conducted to: i) characterize the morphology and phenology of Echinochloa accessions from Arkansas in a common garden; ii) verify the species identity of these accessions based on their morphological traits, and iii) evaluate the dormancy characteristics of Echinochloa accessions. Junglerice (E. colona) was identified as the most common species, comprising about 78% of the accessions collected, with barnyardgrass (E. crus-galli) and …

High Throughput Phenotypic Evaluation Of Drought-Related Traits In Soybean, Hua Bai

Graduate Theses and Dissertations

Drought limits crop growth and yield in soybean. Rapid and effective methods of screening large numbers of soybean lines for drought tolerance are urgently needed. Two experiments were conducted to evaluate the effects of drought in soybean during reproductive stages. In the first experiment five genotypes from maturity groups 2 through 5 were tested under well-irrigated and drought conditions. Beginning at R5, leaf samples were taken for nitrogen concentration analysis. Pictures were taken across the top of each plot to determine the intensity of greenness using the Dark Green Color Index (DGCI). Aerial photographs were also taken to determine aerial …

Comparative Evolutionary Analysis Of Organellar Genomic Diversity In Green Plants, Weishu Fan

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

The mitochondrial genome (mitogenome) and plastid genome (plastome) of plants vary immensely in genome size and gene content. They have also developed several eccentric features, such as the preference for horizontal gene transfer of mitochondrial genes, the reduction of the plastome in non-photosynthetic plants, and variable amounts of RNA editing affecting both genomes. Different organismal lifestyles can partially account for the highly diverse organellar genomes across the tree of green plants. For example, endosymbiotic and parasitic lifestyles can dramatically affect the genomic architectures of plant mitochondria and plastids. In this study, the organellar genomes of several green plants with atypical …

Development And Assessment Of A Groundwater Sustainability Index In Climatically Diverse Groundwater Irrigated Regions In Nebraska, Maria A. Mulet Jalil

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

The aim of this research was to evaluate the impact of regional change in ET on groundwater level changes and the assessment and development of a groundwater sustainability index for climatically diverse regions across Nebraska during 2000-2014. Irrigation in the selected regions is predominantly supplied by groundwater. The hypothesis is that groundwater use can become sustainable if the regional evapotranspiration (ET) is managed so that it equals the ET of vegetation that is native to the region. Site locations were Box Butte, Chase, Dundy, Holt LNNRD and York Counties and 3 ecosystems were evaluated: native vegetation, dryland and irrigated cropping …

Cross Species Selection Scans Identify Components Of C4 Photosynthesis In The Grasses, Pu Huang, Anthony J. Studer, James C. Schnable, Elizabeth A. Kellogg, Thomas P. Brutnell

Department of Agronomy and Horticulture: Faculty Publications

C₄ photosynthesis is perhaps one of the best examples of convergent adaptive evolution with over 25 independent origins in the grasses (Poaceae) alone. The availability of high quality grass genome sequences presents new opportunities to explore the mechanisms underlying this complex trait using evolutionary biology-based approaches. In this study, we performed genome-wide cross-species selection scans in C₄ lineages to facilitate discovery of C₄ genes. The study was enabled by the well conserved collinearity of grass genomes and the recently sequenced genome of a C₃ panicoid grass, Dichanthelium oligosanthes. This method, in contrast to previous studies, …

Reducing Pollen Dispersal Using Forest Windbreaks, Carol Auer, Thomas Meyer, Vernie Sagun

Plant Science Articles

The adoption of genetically engineered (GE) crops has created a demand for practical methods to mitigate pollen dispersal and gene flow. The goal of this project was to measure the ability of a narrow forest windbreak to reduce downwind pollen fluxes from switchgrass (Panicum virgatum L.), a North American grass and model biofuels feedstock. Switchgrass fields were established in two identical plots where one had a forest windbreak and the other was in an open (control) site. Switchgrass reproduction, pollen dispersal, wind speed, and wind direction were measured over two years. Daily release of switchgrass pollen peaked at 11:00-13:30 …

Effect Of Bacteria Isolates In Powdery Mildew Control In Flowering Dogwoods (Cornus Florida L.), Margaret T. Mmbaga, Frank A. Mrema, Lucas Mackasmiel, Emily Rotich

Agricultural and Environmental Sciences Faculty Research

Five bacterial isolates collected from dogwood leaves were evaluated for powdery mildew control in shadehouse and greenhouse environments by using foliar sprays and/or root drenching. Two isolates displayed superior bioactivity and suppressed powdery mildew similar to conventional fungicide thiophanate methyl (Cleary’s 3336F®). The two bacteria disrupted powdery mildew spore germination and ruptured spore membranes causing spore lyses. Bacterial filtrates without bacterial cells were also effective in suppressing powdery mildew and disrupting spore germination and suggested the involvement of secondary metabolites. The two biocontrol agents (BCAs) colonized roots endophytically and promoted plant growth.

High-Input Management Systems Effect On Soybean Seed Yield, Yield Components, And Economic Break-Even Probabilities, John M. Orlowski, Bryson J. Haverkamp, Randall G. Laurenz, David A. Marburger, Eric W. Wilson, Shaun N. Casteel, Shawn P. Conley, Seth L. Naeve, Emerson D. Nafziger, Kraig L. Roozeboom, William J. Ross, Kurt D. Thelen, Chad Lee

Plant and Soil Sciences Faculty Publications

Elevated soybean [Glycine max (L.) Merr.] prices have spurred interest in maximizing soybean seed yield and has led growers to increase the number of inputs in their production systems. However, little information exists about the effects of high-input management on soybean yield and profitability. The purpose of this study was to investigate the effects of individual inputs, as well as combinations of inputs marketed to protect or increase soybean seed yield, yield components, and economic break-even probabilities. Studies were established in nine states and three soybean growing regions (North, Central, and South) between 2012 and 2014. In each site-year …

Distribution Of Genomic Variation In The Usda Soybean Germplasm Collection And Relationship With Phenotypic Variation, Nonoy Batiller Bandillo

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

The USDA Soybean Germplasm Collection harbors a large stock of genetic diversity with potential to accelerate soybean cultivar development. The extent and nature of favorable alleles contained in the collection are not well known nor is the distribution of genetic variation and how it relates to phenotypic variation. The genotyping of the entire USDA Soybean Germplasm Collection marked the beginning of a systematic exploration of genetic diversity for genetic research and breeding. In this research, we conducted the first comprehensive analysis of population structure on the collection of ~14,400 soybean accessions [Glycine max (L.) Merr. and G. soja Siebold …

Herbicide Resistantsorghum Mutants, Ismail M. Dweikat

Department of Agronomy and Horticulture: Faculty Publications

This disclosure provides for four different sorghum mutants that exhibit resistance to ALS-inhibiting herbicides. This dis closure also provides for methods of using such Sorghum mutants that exhibit resistance to ALS-inhibiting herbicides in breeding methods to make Sorghum hybrids, varieties, or lines. The Sorghum hybrids, varieties, and lines provided in this disclosure can be used in methods of controlling weeds.

Expression Of A Constitutively Active Nitrate Reductase Variant In Tobacco Reduces Tobacco-Specific Nitrosamine Accumulation In Cured Leaves And Cigarette Smoke, Jianli Lu, Leichen Zhang, Ramsey S. Lewis, Lucien Bovet, Simon Goepfert, Anne M. Jack, James D. Crutchfield, Huihua Ji, Ralph E. Dewey

Kentucky Tobacco Research and Development Center Faculty Publications

Burley tobaccos (Nicotiana tabacum) display a nitrogen-use-deficiency phenotype that is associated with the accumulation of high levels of nitrate within the leaf, a trait correlated with production of a class of compounds referred to as tobacco-specific nitrosamines (TSNAs). Two TSNA species, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N-nitrosonornicotine (NNN), have been shown to be strong carcinogens in numerous animal studies. We investigated the potential of molecular genetic strategies to lower nitrate levels in burley tobaccos by overexpressing genes encoding key enzymes of the nitrogen-assimilation pathway. Of the various constructs tested, only the expression of a constitutively active nitrate reductase (NR) …

Long-Term Sandhills Prairie Responses To Precipitation, Temperature, And Cattle Stocking Rate, John A. Guretzky, Cheryl Dunn, Heidi L. Hillhouse

Department of Agronomy and Horticulture: Faculty Publications

Understanding of Sandhills prairie, the most expansive sand dune region stabilized by perennial grasses in the Western Hemisphere, is limited by lack of long-term vegetation data. We used a 26-year dataset to evaluate Sandhills prairie responses to yearto- year variation in precipitation, temperature, and cattle stocking rate. Basal cover, a measurement that is constant seasonally and used to detect long-term changes in bunchgrass vegetation, was measured in 38–40 permanent plots positioned along four transects spanning 769 ha from 1979 to 2007. Across this period, total basal cover averaged 2.4 % and was dominated by warm-season grasses (81.1 %). Schizachyrium scoparium …

Physiological And Molecular Characterisation Of Lucerne (Medicago Sativa L.) Germplasm With Improved Seedling Freezing Tolerance, M. Rokebul Anowar, Anne Fennell, Arvid Boe, Ivan W. Mott, Michael D. Peel, Yajun Wu

Agronomy, Horticulture and Plant Science Faculty Publications

We conducted greenhouse experiments to compare 14 lucerne (alfalfa, Medicago sativa L.) germplasms for their survival following freezing. Some are collections adapted to the Grand River National Grasslands in South Dakota. We hypothesised that these collections might have developed a tolerance to survive the frigid growth conditions common there. Two of these collections, River side (RS) and Foster ranch (FR), showed greater freezing tolerance than the other germplasms tested, based on their consistent survival rates with or without cold acclimation. In multiple freezing studies, RS and FR had average survival rates of 74% and 79%, respectively, in contrast to the …

How Does Agroforestry Help Crop Pollination?

Working Trees (USDA-NAC)

Agroforestry helps crop pollination via enhanced pollination efficiency, pollinator habitat, and pollinator protection.

Crop Selection, Cost Analysis, And Irrigation System Design For The Replanting Of A Nut Orchard, Maximilian Bricker

BioResource and Agricultural Engineering

This report was made to help the landowner of Bricker Farms make decisions regarding the replanting of his orchard. The decisions that need to be made in this process include: which crop to plant, how to plant it, and how to improve the distribution uniformity of irrigation water on the orchard. The report does not give definitive final decisions, but presents viable options that the landowner can utilize when deciding. In addition to the options that are presented, the report offers suggestions to the landowner so that the replanting process is done properly in a timely and economically-friendly manner.

Genetic Engineering And Sustainable Crop Disease Management: Opportunities For Case-By-Case Decision-Making, Paul Vincelli

Plant Pathology Faculty Publications

Genetic engineering (GE) offers an expanding array of strategies for enhancing disease resistance of crop plants in sustainable ways, including the potential for reduced pesticide usage. Certain GE applications involve transgenesis, in some cases creating a metabolic pathway novel to the GE crop. In other cases, only cisgenessis is employed. In yet other cases, engineered genetic changes can be so minimal as to be indistinguishable from natural mutations. Thus, GE crops vary substantially and should be evaluated for risks, benefits, and social considerations on a case-by-case basis. Deployment of GE traits should be with an eye towards long-term sustainability; several …

Compost Land Management And Soil Carbon Sequestration, Kylene A. Hohman

Senior Honors Projects, 2010-2019

Extensive fossil fuel burning has released carbon dioxide into the atmosphere. Under proper ecological conditions plants convert atmospheric carbon dioxide into stable soil organic matter, a natural and efficient means of mitigating climate change. In the symbiotic relationship between mycorrhizae and plants, mycorrhizae provide plants with essential nutrients in exchange for carbon sugars leaked from the plants. Mycorrhizae convert carbon sugars to an exudate called glomalin, a protein that assists in developing soil aggregates composed of sand, silt, and clay. These aggregates, called humus, store carbon for hundreds of years under healthy ecological conditions. Compost prompts soil microbes to aerobically …

A Brief History Of Corn: Looking Back To Move Forward, Jon Derek Pruitt

Doctor of Plant Health Program: Dissertations and Student Research

Maize was domesticated from teosinte in Mexico some 7,000 to 10,000 years ago and quickly spread through the Americas. It has become one of the most important crops at a local and global level. Two types, Northern Flint corn and Southern Dent corns provided the basis of the genetic background of modern maize hybrids. The development of hybrids, first double-cross and later single-cross hybrids, along with a transition to high input farming provided huge yield increases, which have continued to improve with improving technology.

Increase in maize production also caused a rise in Western corn Rootworm (Diabrotica virgifera virgifera …

Arkansas Soybean Research Studies 2014, Jeremy Ross

Arkansas Agricultural Experiment Station Research Series

No abstract provided.

Assessment Of An Industrial Type Radiant Heating System For Drying Rough Rice, Anne Adhiambo Okeyo

Graduate Theses and Dissertations

Rough rice is normally harvested at moisture contents (MCs) higher than that for safe storage. The objective for this study was to investigate the effectiveness of scaled-up infrared (IR) heating followed by tempering steps to dry freshly-harvested rough rice. An industrial type, pilot scale, IR drying equipment, designed to convey rough rice on a vibrating conveyor belt was used in this study. The heating zone of the equipment had catalytic IR emitters powered by natural gas. Freshly-harvested rough rice of long-grain pureline (cv. Cheniere), long-grain hybrid (cv. 6XP 756) and medium-grain (cv. CL 271) cultivars at initial moisture contents (IMCs) …

Heat Stress Effects On Cotton During Reproductive Development And Subsequent Acclimation Responses, Toby Ryan Fitzsimons

Graduate Theses and Dissertations

High temperature stress is among the most difficult to control abiotic factors affecting crop yields in the Southern United States due to its wide regional influence. Cotton (Gossypium hirsutum L.) though a tropical plant in origin, it is sensitive to the effects of high temperature. This is of particular concern when the warmest temperatures coincide with the most sensitive developmental stage of flowering. Thus, the capacity to improve cotton’s ability to tolerate heat stress has been a significant focus for many decades. Therefore, this research was composed of several different components all designed to investigate heat stress effects. Using a …

Cover Crop Mixture Diversity And Function, Angela Florence

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

The objective of this study was to evaluate the effect of cover crop mixture diversity on cover crop function. Specifically, this study evaluated the effect of cover crop species and functional richness on aboveground biomass productivity, weed suppression, soil nutrient retention, soil microbial community characteristics, and performance stability. Twenty to forty cover crop treatments were replicated three to four times at eleven sites across southeastern Nebraska using a pool of eighteen species representing three cover crop species each from six pre-defined functional groups: cool-season grasses, cool-season legumes, cool-season brassicas, warm-season grasses, warm-season legumes, and warm-season broadleaves. Each species was planted …